Boiler low water cut-off



Feb. 7, 1939. l EATON 2,146,568

BOILER LOW WATER CUT-OFF' Original Filed July 14, 1934 l rwerwt or: John Eaton Patented Feb. 7, 1939 2,146,568

UNITED STATES .PATENT OFFICE 2,146,568 BOILER LOW WATER CUT-OFF John Eaton, Schenectady, N. Y., assigner to General Electric Company, a corporation of New York Original application- July 14, 1934, Serial No. 735.103. Divided and this application May 21, 1937, Serial No. 143,993

3 Claims. (Cl. 200-122l This application is a division oi my application, to the plate l5 by means of the screws i1 with Serial No. 735,103, led July 14, 1934, relating the packing rings I8 and I9 interposed between to automatic iuel burner control systems and the end of the collar I4 and the plate I6. This apparatus, provides a water-tight seal in the mounting o1' The principal object of the present invention the tube l0 in the side of the boiler is t falls below a predetermined safe value, although in the boiler by means of the mount! lo the device can be used in other service wherever 2 A bimetallic thermostatic element 22 is 10 yit is desired to detect the presence and absence mounted at the free end of the post 20 and exof a heat conducting fluid. tends into latching relation with the cutout The improved form of fluid iesponsive cutoff switch operating member 23. v

or the present invention 1s of the electrically As shown more clearly in Fig 2 the cutout l5 heated thermostatie switch type and operates switch operating member 2li is provided with a, 15

maintains the thermostatic element below the member 222i), preferably a'strip or bar of insu- ZU temperature value at which the switch is opened. lating material, is pivotally mounted between the 20 Whenever there is no water or other iiuid to legs 23a on the cotter pin 25 and carries the mov- 5 mostatic element is mounted at one end of an 8 as long as the bimetallic element 22 remains in 25 ,3U conducting member and the heat is conducted lating material. The switch operating member 30 :D nui winding 3D which is provided with the two ter- 35 In the accompanying drawing, Fig. 1 is a secminal connections 3 i so that it may be connected tional View of a preferred form of the improved in circuit with the oil burner operating mech- Fig. 2 is a front view showing the arrangement the reference character 32 for energization when- 0 of the switch mechanism and the terminal ever the burner is in operation. It will be under- 40 t the presto an electrically controlled fuel burner boiler. ence and absence of liquid in other service. 5 As shown in Fig. l the low water cutoff con- In the boiler low water cutoff service illustrat- 45 sists of a tubel which is adapted to be mounted ed in Fig. 3, the operation of the device is as in an opening provided in the side of the boiler follows: As long as the boiler water surrounds wall H at the minimum safe low water level line. the tube I0, the heat generated by the heater As shown the internally threaded boss i2 is welewinding 30 is conducted by the post 20 to the U ed tothe boiler walls H at i3 and the tube l0 is closed end of the tube I0 and thence into the 50 l5 threaded thereon. The plate I6 which is se- 23 is released. However, as soon as the boiler 5 cured to the open end of the tube I0 is clamped water level falls below that of the tube l0 in the 55 boiler, the heat accumulates in the post 20 and is transmitted to the thermal element 22 to raise the temperature of the latter. At a predetermined temperature the free end of the element 22 is moved to disengage the switch operating member 23 and permit the spring 29 to operate the bridging contact 26 to the circuit opening position. This disconnects all of oil burner mechanism'and control apparatus from the supply line L1 as indicated in Fig. 3. When the low Water condition of the boiler has been corrected and the thermostatic element 22 has returned to normal temperature, the cutout switch mechanism may be reset into operating condition by manually pushing the upturned end 23o of the operating member23 against the bias of spring 29 so as to reengage the upper end of the member 23 in latching relation with the thermal element 22.

In Fig. 3, electric power is supplied tothe burner and control mechanism from the supply line L1, L2. The electric power supply circuit extends from supply line L1 through the switch 33 which is opened whenever the flue door 34 opens due to excessive pressure in the combustion chamber of the boiler ll. The electric power supply circuit then extends through the contacts 21 and the movable switch member 26 of the low water cutout` switch to the burner and control mechanismindicated diagrammatically at 32. This mechanism may be of any conventional type, although preferably of the type shown in my application, Serial No. 735,103, led July 14, 1934. The burner and control mechanism are operated in the usual manner under the control of the room thermostat T and the heating coils 30 of .the low water cutoff prererably is connected to be energized only when the burner is in operation, although it may be energized continuously if desired.

What I claim as new and desire to secure by' sively to the rise in temperature of the post when the boiler water falls below said line.

2. In a fluid detector, the combination of a uid contact member, a post of heat conducting material mounted in heat conducting relation therewith, an electric heater for heating the post, and a bimetallic thermostatic element mounted on the post for operation in response to the change in temperature thereof upon the presence and absence of fluid contact with said member.

3. In a fluid detector, the combination of an elongated member of heat conducting material having one end thereof in heat conductive relation with the fluid, electrical means for centrally heating said member, and a bimetallic thermostatic control member mounted in heat conductive relation with the other end of said member for operation in response to the change in temperature of said otherend upon the presence and rabsence of the uid heat conductive relation at said one end thereof.

JOHN EATON. 

